


The heart's a muscle, too

by just_a_wavefunction



Category: Free!
Genre: F/F, Falling In Love, I took the muscle thing and ran with it, Just gals being pals, Muscles, Pool dates, Swimming, Teenage Flirting, Texting, kou is as dramatic as her brother, physical attraction
Language: English
Status: Completed
Published: 2019-11-10
Updated: 2019-11-10
Packaged: 2021-01-27 02:56:21
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,120
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21384931
Author URL: https://archiveofourown.org/users/just_a_wavefunction/pseuds/just_a_wavefunction
Summary: In which Kou isn't sure whether or not she and Isuzu are flirting, and all of the guys she asks for help are completely useless.(Or: the yuri spin-off that we deserve)
Relationships: Hazuki Nagisa & Matsuoka Gou & Ryuugazaki Rei, Matsuoka Gou & Matsuoka Rin, Matsuoka Gou & Nanase Haruka & Tachibana Makoto, Matsuoka Gou & Yamazaki Sousuke, Matsuoka Gou/Mikoshiba Isuzu, Minor or Background Relationship(s)
Comments: 7
Kudos: 35





	The heart's a muscle, too

**Author's Note:**

> Why am I getting back into free! in the year of our lord 2019? Who knows? I sure don't
> 
> I'll be honest. Dive to the Future hasn't given me much but it has given me Isuzu Mikoshiba and for that I am grateful
> 
> (Side pairings are Reigisa and Mako/Haru/Rin, but they barely take up any space so don't worry about that :) )
> 
> <3

There are different ways, as Kou is well aware, to be obsessed with muscles.

Her obsession goes something like: _Oh, those look great. I want to stare at them. I want to watch them move. I want to see what those abs can do, what those pecs look like with water running over them, whether those shoulders might be able to lift me, what those biceps would feel like around my waist. I want to touch them_, occasionally. (_I want to lick them_, even, though only in her wildest moments because she's not that shameless.)

It doesn't take her long to figure out that Mikoshiba Isuzu's obsession is of a different kind. When Isuzu talks about muscles, it's all: _I want to be like that._

The sleepover with Ayumu and Isuzu is fun, right up until it's not.

Kou isn't friends with a lot of girls at her school, exactly. Sure, there's Chigusa, and now Ayumu, but other than that she prefers to hang out with guys like Nagisa and Rei, or Haru and Makoto, when they were still in Iwatobi. As a result, she never had the full sleepover experience that other girls in her class occasionally mention, what with nail-painting and ice-cream-eating and boy-talking.

There's no nail-painting at this sleepover, only minimal boy-talking, and a sad lack of ice-cream-eating. Instead, Ayumu completely messes up the kitchen while trying to make pop corn, Kou forces them to watch more than two hours of old olympic swimming footage, and Isuzu starts a viciously competitive pillow fight (that she wins by a wide margin). When they decide it's time to sleep, Kou is more exhausted and fired up than she's been in a while, and her sides hurt from laughing.

And then, Ayumu hogs the bathroom for half an hour, and Isuzu declares she doesn't want to wait any longer and takes her shirt off to change, and Kou sees the abs.

They're … nice abs. Objectively, of course, they're not the most defined abs she's seen, because oh boy, she has seen a lot of abs. But there's something about the way they melt into slightly wider hips, the way they're framed by a strip of black underwear and a khaki green sports bra, that makes Kou wonder why she hasn't looked at women's muscles the way she has at men's up until now, because wow, she has been missing out.

And then she realises that she's staring. At a girl she barely knows. Right before they are about to go to sleep.

She turns away so fast that her hair whips around. Luckily, Isuzu seems oblivious to Kou's internal struggle, merrily changing into her pyjamas. When Ayumu finally emerges from the bathroom, Kou has herself under control once more, and the night proceeds without any more hiccups.

Maybe, if she's lucky, Kou thinks right before falling asleep, she'll just forget about it.

She does not forget about it.

Isuzu lives in Tokyo and they don't exactly see each other a lot, but Kou has her phone number. And so, when she spots a particularly impressive set of abs in one of her men's muscle magazines, she snaps a picture and sends it to Isuzu. She doesn't think much of it; as a fellow muscle enthusiast, she practically considers it her duty to share her findings.

Isuzu sends an abs picture back, and it takes Kou a second to recognise the shape, the skin tone, the waist, the sports bra.

_So cool_, the caption reads. _I'll need to train a lot harder if I ever want to look like that!! :P_

Kou stares at the picture far longer than at the one in the muscle magazine.

_You can do it_, she writes back with only minimal hesitation. _I believe in you!_

And then, she adds,_ Just keep me updated on your progress :)_ and hits send before she can chicken out.

It becomes something of a game, then. Kou sends a picture of a bulging biceps, Isuzu sends a close-up of her arm-wrestling her younger brother. Kou sends some well-defined calves, Isuzu responds with a shot of her own leg propped up on the edge of a bathtub, with a little bit of ginger stubble. Kou sends a torso, Isuzu sends a selfie of her hitting the gym.

The day Kou notices something's off is when she happens across a photo of some extremely attractive back muscles. The guy they belong to has turned his head to the side to look at the camera, and he's throwing a careless smile over his shoulder. His face is not particularly interesting, but his lats really are something; as per usual, Kou snaps a picture and sends it to Isuzu.

What she gets back nearly makes her throw her phone across the room.

Because what she gets back is this: Isuzu in her bathroom, with her back to the camera. The warm light sets off the ripple of muscles across her skin and the smattering of freckles on her shoulders. One of her hands is in her hair, recently cut shorter at the neck; her shoulder blade casts a sharp shadow. Like the guy in the picture, she's turned her head to the side to look at the camera.

Unlike the guy in the picture, her smile isn't careless. It's sharp, and brilliant, and inviting, and it makes Kou's knees feel like jelly.

Isuzu is not wearing a sports bra this time.

_Not bad_, Kou types back with shaking fingers, wondering what on earth she has gotten herself into.

“I need your help,” she tells Rin over the phone a few days later.

“Hang on a sec – ” She holds her phone away from her ear just in time to tune out Rin screaming at his roommates in loud English. “Okay, they're leaving now. What d'you need?”

Kou worries her lip, unsure about how to word her question. “How did you know you liked guys?”

There's silence at the end of the line.

“Is there a guy you like?” Rin says eventually.

“No!” Kou groans in frustration. “I mean, how did you know you were gay?”

“Is there a _girl_ you like?”

“I don't know! That's what I'm trying to figure out!”

“Um – fuck. Look, I'm really not in a great position to answer this. Have you tried, I don't know, aggressively making out with her after swimming practice? That worked for me.”

Oh God, and now she's picturing Isuzu coming out of the pool in a two-piece swimsuit, water running down her stomach, and Kou is waiting for her in the changing rooms where Isuzu just sort of pins her against the lockers and leans over her until her wet hair brushes Kou's cheek, and then she kisses the living daylights out of her –

“Are you thinking about it right now?”

“Yes!” Kou whines. “And it's not helping!”

Rin laughs in that way that makes Kou want to punch him in the face. “Wow, my sister is having her own moment of same-sex panic.” She can just see him wipe an imaginary tear from his eye. “I'm so proud.”

“I hate you,” she declares and hangs up.

Desperate times call for desperate measures, Kou tells herself as she sits Nagisa an Rei down at their clubroom table after practice. _Really_ desperate measures.

“Nagisa! Rei!”

Rei flinches at her tone. “Yes, Ma'am!”

Kou takes a deep breath and looks at both of them. “How did you know you were into each other?”

Rei goes beet-red at the question; Nagisa looks like he's waited his whole life to hear it.

“It was love at first sight!” he declares. “I was immediately charmed by Rei-chan's calves of steel and icy demeanour.”

Rei splutters for a while at that. “You spent most of the time after our first meeting harassing me to join the swimming club!”

“That's because I wanted you by my side! Of course,” he adds sagely, “it took Rei-chan much longer to become receptive to my charms, in return.”

Rei adjusts his glasses and mumbles something.

“What was that, Rei-chan?”

He clears his throat. “I said, not _that_ much longer.”

Nagisa's eyes widen. “Rei-chan! You had a crush on me?”

“We've been dating for several months, I fail to see how that is relevant _now_ – ”

“Of course it's relevant, Haru-chan and Kou-chan ran a _betting pool_ about us, tell him, Kou-chan – ”

“You did _what_ now?!”

Kou sighs. She doesn't know what she expected.

She doesn't stop sending Isuzu pictures, is the thing. Neither does Isuzu.

They don't get any more risqué than the back picture, on the contrary. Of course Isuzu still sends her updates on her training (including muscle groups Kou didn't even know she liked), but now and again, she'll slip in a selfie with a cute cat she met on the pavement. A picture of her wide grin after winning a particularly tough arcade game. A goofy face she makes at her camera right before going to sleep, head already on her pillow.

It's these pictures that have nothing to do with showing off muscles (or, dare she think it, flirting) that make Kou most nervous of all, because they mean there's something to lose.

Tentatively, she starts sending pictures of herself back. Drinking a milk shake in her favourite café (_Looks delicious :P_)_._ Trying out a new skirt at the shopping mall (_Cute!! ò.ó_). She once spends nearly fifteen minutes trying to get a perfect shot of herself at Iwatobi's beach, with the strap of her bikini just in frame.

Twenty seconds after hitting send on that last one, her phone rings.

“I didn't know you swam!” Isuzu says without preamble. Her excitement almost makes the phone vibrate.

“Well, I – I don't really,” Kou says, taken aback. “Rin is the one who swims in the family, and there's no way I'm doing the same thing as my brother.”

Belatedly, she realises that she's talking to a Mikoshiba sibling.

“Huh,” Isuzu says. “Why not? All you have to do is be better at it than him!”

Kou giggles at her unwavering confidence. “Is that strategy working with your brothers?”

“Not always when we're swimming,” Isuzu admits, and then adds, “But so far, it's working pretty well with you.”

The laugh gets stuck in Kou's throat, this time. She doesn't know what to say; all she knows is that the flush she feels on her face has nothing to do with the sun. Isuzu, meanwhile, is still talking.

“Damn, I just winked, but I forgot you can't see it. Obviously. Hey, imagine I winked through your phone, okay? This distance thing sucks. When's the next time you can come to Tokyo?”

“I have a free weekend in two weeks,” Kou answers on autopilot. This, at least, is something she knows. “I could come over.”

“Awesome! I have a competition then, you can watch me. And we should go swim together afterwards! Not racing, obviously, just for fun.” There's a pause in which Kou hears Isuzu breathe deeply. “The pool is really pretty at night.”

Kou swallows. “That sounds great.”

“I know! That's why I suggested it! Well, see you soon, Kou!”

For a few moments, Kou listens to the beeping of Isuzu's phone disconnecting. She buries her toes in the sand.

She is _so_ far gone.

“How do you know if someone likes you back?” she asks Sousuke later over the phone.

“It's very sweet of you to trust me with this,” comes the careful reply, “but honestly, Kou, how the fuck should I know?”

Kou sighs. “I've tried talking to Rin, and Nagisa and Rei, but they're all useless. I'm running out of options.” Distantly, she wonders why nobody seems to know any girls around here. She could really use some good female advice, even though the only reference point she has on that are Amakata-sensei's obscure proverbs, and those aren't any help, either.

“Okay.” There's a moment of rustling as Sousuke shifts his phone to the other shoulder and grabs a pen and a sheet of paper like he's the head of a detective agency. “What are we working with?”

“I send her pictures of random muscles I find,” Kou says. “She sends me pictures of her own muscles. On her own body. Her own, not-very-clothed body.”

Sousuke takes a while to react to that.

“Well.” He clears his throat. “That sounds pretty straight-forward.”

“She also sends me good-night selfies with silly expressions and invites me to go to the pool with her at night.”

“I'll correct earlier my statement. That sounds _extremely_ straight-forward.”

“Is it, though?” Kou asks, nervously twirling a strand of hair around her finger. “It could still be platonic, right? Just gals being pals?”

“I can see that you're related to Rin,” Sousuke says.

One day, at four a.m., Kou stumbles across a video of a football player crushing a football between his thighs.

She bites her lip, then forwards the link to Isuzu.

_That's badass_, comes the quick reply.

Kou decides not to wonder what Isuzu is doing awake at that time; she's in no place to judge.

_Isn't it?_ she writes back. _Imagine if that were a head!_

_Ew, Kou! Gross!!!_

Two days later, Isuzu sends her a video. She's in the showers after swimming practice, surrounded by her team members (one of whom must be holding the phone). Somebody off-screen hands her a watermelon. Isuzu grins at the camera, places the watermelon between her thighs, and squeezes. It bursts and splatters on the floor to a chorus of her teammates' triumphant cheers.

_How's that for a head?? _is Isuzu's caption.

_Now THAT'S gross_, Kou types, then rewatches the video twenty-four times.

Kou decides to take the early train to Tokyo, because there's still one source of advice she hasn't tapped into, even though she isn't sure she wants to.

Besides, since Sousuke isn't around that weekend, she does need a place to stay, and Makoto makes a mean breakfast.

“I have a question,” she says once they're all seated around the table with a cup of tea.

“Fire away,” Makoto says with a smile. Haru says nothing, which is all the encouragement she can expect from him.

“You and Rin. That's a long-distance-thing, right? So you send each other pictures?”

“Uh.” Makoto glances over at Haru.

Haru nods gravely. “A lot of pictures.”

Kou presses her palms together. “Cute pictures?”

“Yes.”

“But also _suggestive _pictures?”

“_All of_ the pictures.”

“I'm really not sure where you're going with this,” Makoto interjects weakly.

“It's obvious, Makoto,” Haru says, and Kou could weep with joy. Leave it to Haru to finally understand what she's going through.

“Is it though?” Makoto says.

“Yes. She needs our help.” Haru turns to her. “Don't worry. I will help you take the perfect suggestive picture.”

“Haru!”

Kou freezes at the table. “That's … really not what I meant.”

Haru blinks. “Never mind then.”

“It's just – ” She sighs in frustration. “I've been sending pictures back and forth with this girl, and some of them _may _have been a little bit suggestive, and now I'm trying to figure out whether she's flirting with me or not, and whether_ I'm _flirting with her or not, and I thought, since the three of you somehow got your act together, you might have some advice for me.”

Makoto's expression grows pensive. He glances at Haru, who glances back at him, and Kou is starting to see what her brother means whenever he mentions their freaky telepathy thing.

“We might not be the best people to ask,” Makoto finally allows. “It took Haru forever to realise that I liked him – ”

“And vice versa,” Haru mumbles pointedly.

“ – and from then on to figuring out the thing with Rin, it's … well, we made it a lot more complicated than it needed to be. Which is to say,” he adds at Kou's dismayed face, “don't do what we did! You're a lovely girl, Kou. So just go for it, right?”

Kou nods slowly, curling her hands into fists on the table.

Go for it. Right.

Isuzu places first in her competition, and Kou finds herself cheering louder than she ever has before. She climbs out of the water like a majestic polar bear who has just hunted down an entire family of seals, fluidly rising to her full height, water dripping down her arms, and Jesus Christ, Kou has no chill left at all, does she?

She manages to sneak into the locker rooms and hangs back until most of the girls have left. Isuzu spots her in the doorway and waves her over with a wide grin; she's still in her swimsuit, even though she has mostly dried off. Kou can't help but stare for a moment.

“Kou!” Isuzu says, grasping her hands. “You made it.”

Kou smiles at her friend and sits down next to her on the plastic bench. “I wouldn't have wanted to miss that! You were great out there.”

Isuzu's smile turns a little bit crooked. “You think so?”

“Definitely.” Makoto's words are echoing through her head. _Just go for it._ She swallows. “I found a picture of some really nice thighs. I was going to send it to you, for good luck, but it looks like you didn't need that.”

“My own thighs are doing the job pretty well,” Isuzu agrees with a twinkle in her eyes.

And slowly, very slowly, so that Kou can pull away if she wants to, Isuzu picks up Kou's right hand and runs it up her thigh. Kou bites her lip; she can't look Isuzu in her eyes, can only stare at their linked hands on Isuzu's leg climbing higher. Except Isuzu's hand is shaking, and then Kou does look up and sees the insecurity, the question there.

And suddenly, she isn't sure she knows the answer.

She stops her hand from moving, still on Isuzu's leg. They stay like that for nearly a full minute, until Kou pulls away just a little bit, maybe to shift to a better position, maybe to move in again, but not to reject, definitely not –

Only that rejection is exactly what Isuzu sees.

She looks away, off to the side where Kou can't catch her eyes anymore.

“Sorry,” she hisses, grabs her towel and the rest of her clothes, and leaves.

It's Haru who opens the door to her that evening.

“I think I screwed up,” she says.

She isn't sure how he does it, but not three minutes later he has manoeuvred her onto Makoto's couch under a comfortable blanket with a cup of hot chocolate, and she thinks she's holding it together pretty well up until Makoto sits down next to her, runs a hand across her back and asks her what's wrong, and she bursts into tears.

She tries to explain everything as best she can, and even though Makoto and Haru are obviously just as useless as the rest of them, they don't actually suck at comforting. Within fifteen minutes, she has calmed down enough to start formulating a plan.

It's obvious that she overestimated Isuzu's confidence. She feels stupid in hindsight: why would Isuzu be any more certain about this thing between them than Kou herself? If she wants to fix this – at the very least, salvage what's left – she'll have to be clear about her intentions. She'll have to put herself out there. Maybe … some sort of gesture. A romantic gesture. Something meaningful to the both of them.

As an idea takes shape in her mind, she feels a smile at the corner of her lips. Her brother would be proud.

She wipes the tears off her face and asks Haru for a phone number she never thought she would call. It connects after only one ring.

“Kou-san! What's the joyful occasion?”

“Mikoshiba Seijuro-san,” she says gravely. “I need a favour.”

She feels a little bit silly when, about an hour later, she's throwing tiny stones against the window of what Seijuro swears is Isuzu's dorm room. She tried texting and calling, but it seems like her phone is turned off, and honestly, Kou can't blame her.

After a few attempts, there is finally some movement in the room, and a girl Kou doesn't recognise comes to the window.

“Is there a Mikoshiba Isuzu here?” Kou asks before the girl gets a word in.

Her eyes widen in understanding. “Guys!” she shouts back into the room. “It's Mikoshiba's girlfriend!”

Kou doesn't bother to correct her. “Can you ask her to come outside, please? I have something important to tell her.”

The girl grins and winks at her. “Leave it to me. We're all rooting for you!”

“And tell her to wear her swim suit!” Kou calls after her, right before the window slams shut.

Isuzu looks wary when she sneaks out of the building, but she's here and that's all Kou can ask for. They walk in silence for a while, with Kou checking on her phone now and again that they're still on the right path.

Beside her, Isuzu sighs quietly. “What do you want from me, Kou?”

“You'll see,” Kou promises and walks on.

It takes a small eternity for them to get to the pool. Kou opens the door with the keys that Seijuro gave her and leads their way through the building to the outdoor area. The night air isn't cold, but it isn't exactly warm, either, definitely not warm enough for swimming, and Kou is beginning to suspect that she didn't really think this through. Before she can lose her nerve, though, she slips out of her clothes and climbs into the water.

“Well?” she says, hiding a shiver and turning towards Isuzu. “Are you coming in?”

Isuzu swallows, maybe because Kou is wearing the swimsuit from her photo at the beach. She sheds her clothes and hops in, as well, not at all like the aquatic predator Kou saw during her competition. This Isuzu is vulnerable, and scared, and Kou knows what that means.

“You wanted to swim with me,” she says. “So let's swim.”

And they do. With a certain distance, at first, carefully, not getting too far ahead of themselves. Kou is the first one to reach out – she splashes some water at Isuzu, who yelps and retaliates immediately. It's natural to continue with this back and forth, all the while drifting closer, just like they've been doing ever since they met.

When they're finally face to face, Isuzu's grin is back full-force, and it's the best thing Kou's ever seen. Her friend points at the sky.

“See?” she says. “That's what I meant. You can see some stars.”

Kou tips her head back and looks for a moment. It never really gets dark in the city, not like in Iwatobi, but Isuzu is right: some stars are out there, valiantly shining. They remind Kou of freckles, right now.

“I'm sorry, Isuzu,” she says. “For not being clear, before, and for letting you run off. This is all very new to me, and I was scared, so I started talking about thighs, but what I meant to say is – ”

She takes a deep breath and a good look at her friend. Isuzu's eyes are wide and shine much brighter than the stars overhead.

“I think you're great. I think you're attractive, and fun, and exciting, and I want to know more about you. And – and I think we should date, I mean, if you want to. Also, your muscles are amazing, I've never seen anything like them before – ”

A wide smile stretches across Isuzu's face, then – not her usual grin, but something much more open. Without warning, she winds her arms around Kou's waist and lifts her up, halfway out of the water.

“Yes,” she says, “wow, yes, I'd really like that. I can't believe I get to date someone as cool as you, seriously, you're the _best_, Kou – ”

As much as Kou likes hearing compliments about herself, there's a time and place for everything, so she leans down, threads her fingers through Isuzu's wet hair and cuts her off with a kiss. It's awkward for just a moment, until Isuzu adjusts her hold on Kou and kisses back properly, at which point Kou is thankful for the support of Isuzu's arms because otherwise she would dissolve right into the water.

There are different ways, as Kou is well aware, to be obsessed with muscles.

Her own obsession hasn't changed that much, if she's honest with herself. Rather, it's now focused on a specific set of muscles belonging to a specific person whom she likes for a lot of other reasons, too.

At least she doesn't have to wonder anymore how those biceps feel around her waist.

**Author's Note:**

> (not pictured: rin's actual tears of pride when kou tells him about the evening at the pool)


End file.
